VOSA. Help and Documentation

Version 6.0, Apr 2018

1. Introduction
2. Input files
2.1. Upload files
2.2. VOSA file format
2.3. Single object
2.4. Manage files
2.5. Archiving
2.6. Filters
3. Objects
3.1. Coordinates
3.2. Distances
3.3. Extinction
4. Build SEDs
4.1. VO photometry
4.2. SED
4.3. Excess
5. Analysis
5.1. Model Fit
5.2. Bayes analysis
5.3. Template Fit
5.4. Templates Bayes
5.5. HR diagram
5.6. Upper Limits
5.7. Statistics
6. Save results
6.1. Download
6.2. SAMP
6.3. References
6.4. Log file
6.5. Plots
7. VOSA Architecture
8. Phys. Constants
9. FAQ
10. Use Case
11. Quality
11.1. Stellar libraries
11.2. VO photometry
12. Credits
13. Helpdesk
14. About

Quality: VO photometry tests

Flux comparison SDSS DR9 / IPHAS DR2 (r,i bands)

Date of this test: 2016/10/08

We have taken a sample of "good" (no quality flags) sample of 200 objects in common in both catalogues and have compared the fluxes provided by VOSA.

Methodology

  • Search around RA:60.0deg DEC:-52.0deg. Radius:0.2deg.
  • Crossmatched using CDS x-match
  • Filtering $0<200&&rErr>0&&iErr>0&&rmag<22.2&&rmag>14&&imag<21.3&&imag>14&&q_mode

Conclusions:

  • r band: No bias. Differences in flux typically less than 10% (figure1)
  • i band: SDSS fluxes are systematically higher. Differences in flux are typically less than 15 % (figure 2).

Flux comparison: APASS DR9 / Johnson (B,V bands)

Date of this test: 2016/10/08

Sample: 100 good sources.

Conclusion: APASS fluxes are systematically higher in both bands (typically 10%) (Figures 3,4).

Flux comparison: SDSS DR9 / VPHAS DR2 (u,g,r,i bands)

Date of this test: 2017/05/08

Sample: we have taken a good quality sample of 119 objects in common in both catalogues and have compared the fluxes provided by VOSA.

Methodology:

  • Search around RA:101.0deg DEC:0.0deg. Radius:0.5deg.
  • Crossmatched using CDS x-match (radius=0.2arcsec).
  • Filtering (magnitudes below the limiting magnitude, errors in magnitude below 0.2 and good quality (qmode, cl=6,clean)
    $0<3000 && umag<22.0 && gmag<22.2 && rmag<22.2 && imag<21.3 && e_umag<0.2 && e_gmag<0.2 && e_rmag<0.2 && e_imag<0.2 && qmode && cl==6 && umag_x<22.0 && gmag_x<22.0 && rmag_x<22.0 && imag_x<22.0 && e_umag_x<0.2 && e_gmag_x<0.2 && e_rmag_x<0.2 && e_imag_x<0.2 && clean

Conclusions:

band u g r i
Median (SDSS/VPHAS+) 0.851 1.023 1.048 1.030
Q10 (SDSS/VPHAS+) 0.701 0.973 1.008 0.977
Q90 (SDSS/VPHAS+) 0.953 1.063 1.085 1.075

u band

g band

r band

i band
>

Flux comparison: SDSS DR9 / PanSTARRS DR1 (g,r,i,z bands)

Date of this test: 2017/05/08

Sample: we have taken a good quality sample of 200 objects in common in both catalogues and have compared the fluxes provided by VOSA.

Methodology:

  • Search around RA:101.0deg DEC:0.0deg. Radius:0.5deg.
  • Crossmatching (radius 0.2 arcsec).
  • Filtering (magnitudes below the limiting magnitude, errors in magnitude below 0.2 and good quality (qmode, cl=6,quality_flag<64)
    $0<201 && contains(toString(q_mode),"+") && cl==6 && umag<22.0 && gmag<22.2 && rmag<22.2 && imag<21.3 && e_umag<0.2 && e_gmag<0.2 && e_rmag<0.2 && e_imag<0.2 && qualityflag<64 && gMeanApMagErr<0.2 && rMeanApMagErr<0.2 && iMeanApMagErr<0.2 && zMeanApMagErr<0.2 && gMeanApMag<23.3 && rMeanApMag<23.2 && iMeanApMag<23.1 && zMeanApMag<22.3

Conclusions:

band g r i z
Median (SDSS/VPHAS+) 0.994 1.011 1.051 ---
Q10 (SDSS/VPHAS+) 0.924 0.972 1.013 ---
Q90 (SDSS/VPHAS+) 1.043 1.032 1.105 ---

g band

r band

i band

z band (No comparison was performed due to the significant differences both in wavelength coverage and shape between the two filters).

Flux comparison: SDSS DR9 / CTIO.DECam (g,r,z bands)

Date of this test: 2017/05/08

Sample: we have taken a good quality sample of 784 objects in common in both catalogues and have compared the fluxes provided by VOSA.

Methodology:

  • Search around RA:328.3deg DEC:17.5deg. Radius:0.5deg.
  • Crossmatching (search radius:0.2arcsec)
  • Filtering (magnitudes below the limiting magnitude, errors in magnitude below 0.2 and good quality (qmode, cl=6,decam_anymask)
    gmag<22.2 && rmag<22.2 && zmag<20.5 && e_gmag<0.2 && e_rmag<0.2 && e_zmag<0.2 && qmode && cl==6 && decam_anymask_1==0 && decam_anymask_2==0 && decam_anymask_3==0 && decam_anymask_4==0 && decam_anymask_5==0 && g<24.7 && r<23.9 && z<23

Conclusions:

band g r z
Median (SDSS/VPHAS+) 0.957 0.973 1.024
Q10 (SDSS/VPHAS+) 0.861 0.882 0.959
Q90 (SDSS/VPHAS+) 1.017 1.018 1.083

g band

r band

z band